The King's power rests in the support of the House of Lords. Should he move against their wishes he will have to do so without their support. This can lead to open revolt or even civil war. It is by the authority of the king and the size of his army that he maintains power in the land.
Many of the March Lords and Barons have challenged the King on minor issues in the past, knowing full-well that the king would spend a small fortune to mobilize his army to thwart their efforts.
The House of Lords forbade the education of arcane magic to any but of Noble Birth within the Marches in the Summer Session in the year 1119 KR. The edict was later revised to apply only to the South Marches after the Northern Lords rallied to halt any advance of the King's Forces from imposing his rule.